1. Field of the Invention
The invention relates to a sealing plug to be used in a watertight connector and to a watertight connector provided with such sealing plug.
2. Description of the Related Art
Japanese Unexamined Utility Model Publication No. S63-3074 and FIG. 7 herein disclose a rubber plug used in a watertight connector. With reference to FIG. 7, the rubber plug 1 closely holds an insulated wire 2 inserted therethrough. The watertight connector includes a housing 3 with a rear surface and a cavity 4 that extends into the rear surface. The plug 1 is insertable into the cavity 4. The plug 1 is formed with a plurality of outer rips 5 that can be brought into close contact with the inner wall of the cavity 4. The rubber plug 1 is fixed to a terminal filling 6 by crimping a barrel 7 of the terminal fitting 6 to the front end of the rubber plug 1. The terminal filling 6 is inserted into the cavity 4 and held in position by a resiliently deformable lock 8 formed in the cavity 4. As a result, the rubber plug 1 engages the inside of the cavity in a watertight manner.
The insulated wire 2 may be displaced backward in the cavity 4 by the repeated expansion and elongation of a covering resin of the insulated wire 2 in a heat-cycle environment. The rubber plug 1 is mounted closely on the insulated wire 2 and may be displaced back in the cavity 4 with the insulated wire 2. Thus, some of the outer lips may come out of the cavity 4 to impair a sealing property.
The invention was developed in view of the above problem and an object thereof is to maintain the sealing property of a sealing plug.